Golf club head

ABSTRACT

An iron-type golf club head is disclosed having a first piece including a portion of an iron-type face. A second piece including a heel portion, a sole portion, a toe portion, a top-line portion, a hinge region, and a front opening for receiving the first piece is also disclosed. A first contact surface of the first piece is connected with a second contact surface of the second piece at a contact interface. A continuous weld extends along the contact interface attaching the first and second pieces together at the contact interface. The continuous weld includes a fusion zone occurring substantially on the iron-type face outside the hinge region of the club head.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/741,286, filed Jan. 14, 2013, which is a divisional of U.S. patentapplication Ser. No. 12/763,014, filed Apr. 19, 2010, which claims thebenefit of U.S. Provisional Patent Application No. 61/214,487, filedApr. 23, 2009, all of which are incorporated herein by reference.

FIELD

The present disclosure relates to a golf club head. More specifically,the present disclosure relates to a golf club head made of multiplepieces that are welded together.

BACKGROUND

A golf set includes various types of clubs for use in differentconditions or circumstances in which a ball is hit during a golf game. Aset of clubs typically includes a “driver” for hitting the ball thelongest distance on a course. A fairway “wood” can be sued for hittingthe ball shorter distances than the driver. A set of irons are used forhitting the ball within a range of distances typically shorter than thedriver or woods.

An iron has a flat face that normally contacts the ball whenever theball is being hit with the iron. Irons have angled faces for achievinglofts ranging from about 18 degrees to about 60 degrees.

Every club has a “sweet spot” that represents the best hitting zone onthe face for maximizing the probability of the golfer achieving the bestand most predictable shot using the particular club. Most golfers striveto make contact with the ball inside the sweet spot to achieve a desiredtrajectory.

In order to withstand repeated ball impacts, the face plate of a golfclub has traditionally been made thick enough to prevent mechanicalfailure.

SUMMARY OF THE DESCRIPTION

The present disclosure describes a golf club head comprising a heelportion, a toe portion, a crown, a sole, and a face.

The foregoing and other objects, features, and advantages of theinvention will become more apparent from the following detaileddescription, which proceeds with reference to the accompanying figures.

According to one aspect of the present invention, an iron-type golf clubhead is described having a first piece including at least a portion ofan iron-type face. A second piece including a heel portion, a soleportion, a toe portion, a top-line portion, a hinge region, and a frontopening for receiving the first piece is also described. A first contactsurface of the first piece is connected with a second contact surface ofthe second piece at a contact interface. A continuous weld extends alongthe contact interface attaching the first and second pieces together atthe contact interface. The continuous weld includes a fusion zoneoccurring substantially on the iron-type face outside the hinge regionof the club head.

In one example, a rear weld bead is exposed on a rear surface of theiron-type face.

In another example, the rear weld bead is substantially covered by athird piece.

In yet another example, a front weld bead is removed from a frontsurface of the iron-type face and a weld centerline axis is offset froma rear wall portion by a distance of at least 1 mm.

In one example, a total face area is about 2,700 mm²-5,000 mm² and athin face area is about 450 mm²-2,020 mm².

In another example, a thin face thickness is about 1.5-2.5 mm or a thinface thickness is in a range of less than 2.0 mm.

In yet another example, a thin face area percentage is about 13-70% andan inverted cone region is about 230 mm² to about 2,000 mm².

In one example, a first piece rear surface area is about 300 mm² toabout 4,000 mm² and a coefficient of restitution is greater than about0.8.

In another example, the first piece is forged of a steel selected fromthe group consisting of maraging steels, maraging stainless steels, andPH stainless steels. The stainless steel is C455 or 17-4 stainlesssteel.

In yet another example, the fusion zone is substantially located in arelatively low impact stress region of the front striking surface.

According to another aspect of the present invention, a golf club headis described having a front striking surface, a rear face surfacelocated behind at least a portion of the front striking surface in acavity region, a first piece including at least a portion of the frontstriking surface, and a second piece including a heel portion, a soleportion, a toe portion, a top-line portion, a hinge region, and a frontopening on the front striking surface for receiving the first piece. Afirst contact surface of the first piece is connected with a secondcontact surface of the second piece at a contact interface. A continuousweld extends along the contact interface attaching the first and secondpieces together at the contact interface. The continuous weld includes afusion zone creating a weld bead on at least the rear face surface. Athird piece is configured to be inserted into the cavity region andattached to the rear face surface. The third piece substantially coversthe weld bead on the rear face surface.

According to another aspect of the present invention, a method isdescribed including placing a continuous weld located on the face of acavity back iron-type golf club head. The weld extends continuously on afront striking surface of the face creating a front and rear weld bead.The weld is located at least partially on a contact interface between afirst piece and a second piece. A method of removing a front weld beadfrom the front striking surface of the face and covering the rear weldbead located on a rear surface of the face with a badge is described.The rear weld bead is obscured by the badge in the cavity back iron-typegolf club head.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and notlimitation in the figures of the accompanying drawings in which likereferences indicate similar elements.

FIG. 1A is an exploded view of an embodiment of a golf club headaccording to the present disclosure.

FIG. 1B is an assembled view of the golf club head of FIG. 1A.

FIG. 2 is an illustration of a golf club head and an impact area.

FIG. 3A is a cross-sectional view of the golf club head taken alongsection lines 3A-3A in FIG. 1B.

FIG. 3B is a magnified view of a weld zone.

FIG. 3C is a magnified view of a weld zone.

FIG. 4 is a cross-sectional view of a golf club head according to anembodiment.

FIG. 5 is a cross-sectional view of a golf club head according to anembodiment.

FIG. 6 is a cross-sectional view of a golf club head according to anembodiment.

FIG. 7 is a cross-sectional view of a golf club head according to anembodiment.

FIG. 8 is a toe perspective view of a golf club head.

FIG. 9 is a cross-sectional view of the golf club head taken alongsection lines 9-9 in FIG. 8.

FIG. 10 is a cross-sectional view of a golf club head according to anembodiment.

FIG. 11 is a cross-sectional view of a golf club head according to anembodiment.

FIG. 12A is an isometric view of a golf club assembly.

FIG. 12B is an isometric view of an assembled golf club head.

FIG. 13 is a flow chart of a golf club assembly operation.

DETAILED DESCRIPTION

Various embodiments and aspects of the inventions will be described withreference to details discussed below, and the accompanying drawings willillustrate the various embodiments. The following description anddrawings are illustrative of the invention and are not to be construedas limiting the invention. Numerous specific details are described toprovide a thorough understanding of various embodiments of the presentinvention. However, in certain instances, well-known or conventionaldetails are not described in order to provide a concise discussion ofembodiments of the present inventions.

FIG. 1A illustrates a golf club head 100 including a first piecestriking plate 118 and a second piece 126. The first piece strikingplate 118 is a portion of a front striking surface. The second piece 126is attached to the first piece 118 to form the golf club head 100.

FIG. 1A further illustrates the first piece striking plate 118 being aportion of the front striking surface of the golf club head 100 andhaving a first piece front surface 120. The first piece front surface120 includes grooves 124 in accordance with The Rules of Golf issued bythe United States Golf Association (USGA). The first piece strikingplate 118 also includes a first contact surface 122 extending away froma perimeter of the front surface 120.

The second piece 126 includes a hosel 102, a hosel axis 104, a soleportion 106, a toe portion 108, a heel portion 110, a top-line portion112, a cavity back wall 113, a front opening 114, and a second contactsurface 116.

FIG. 1B illustrates the golf club head 100 after the first piecestriking plate 118 is inserted into the second piece 126 and welded. Inone embodiment, a front weld bead 128 is formed from a continuous laserweld or plasma weld that extends along a contact interface between thefirst contact surface 122 and second contact surface 116. In certainembodiments, the welding occurs on the front striking surface of thegolf club head 100 while creating a front weld bead 128 on the frontstriking surface and a rear weld bead on the rear face surface locatedbehind a portion of the front striking surface.

FIG. 1B shows the front weld bead 128 created immediately after awelding operation and prior to finishing. In one embodiment, the weldcontour matches the outer profile contours of the top-line portion, thetoe portion, and the sole portion. In one embodiment, the weld contourcan enclose the set of grooves 124 that are machined or cast into thefront piece striking plate 118. In another embodiment, the grooves 124can be added after the welding operation and can overlap with the weldcontour in certain locations.

FIG. 2 shows a golf club head 200 with a front weld contour 216 and theweld contour 216 placement with respect to an impact area. In definingthe impact area, a center line axis 206, a toe offset axis 208, a heeloffset axis 210, a top-line axis 202, a top-line offset axis 204, a soleaxis 214, and a sole offset axis 212 are shown to be coplanar across thestriking face 218 of the golf club head 200. The center line 206 passesthrough an ideal center striking point 220. The toe offset axis 208 andheel offset axis 210 are parallel and coplanar with the center line axis206. The toe offset axis 208 is offset from the center line axis 206 bya distance, d1. The heel offset axis 210 is offset from the center lineaxis 206 by a distance, d2.

The top-line axis 202 is parallel with the top-line edge. In cases wherethe top-line edge is non-linear, the top-line axis 202 is tangent to theoutermost top-line edge while remaining primarily parallel with thetop-line edge. The top-line offset axis 204 is coplanar, parallel, andoffset from the top-line axis 202 by a distance, d3. Similarly, the soleaxis 214 is tangent and primarily parallel with the sole edge. The soleoffset axis 212 is coplanar, parallel, and offset from the sole axis 214by a distance, d4.

In one embodiment, the impact area is defined as the part of the frontstriking face 218 that lies within 0.80 inches (20 mm, dimensions d1,d2)on either side of a vertical center line 206 of the face 218, butexcluding strips that are 0.25 inches (6.35 mm, dimensions d3,d4) widefrom the top and bottom edges of the club head. In other words, theimpact area is defined by the top-line offset axis 204, the toe offsetaxis 208, the heel offset axis 210, and the sole offset axis 212 withina striking face plane.

FIG. 2 further shows the weld contour 216, in one embodiment, extendingat least partially into the impact area. In certain embodiments, theweld contour 216 can be located entirely within the impact area orentirely outside of the impact area.

FIG. 3A shows a cross-sectional view along cross-section lines 3A-3A(passing through a face center point) in FIG. 18. FIG. 3A illustrates across-sectional profile 300 including a cavity back wall 113 forming acavity with the first piece striking plate 118. A weld is created by awelding device 302, such as a laser or plasma weld. In one embodiment,the weld is applied on the front face of the golf club head 300 from afrontward to rearward direction. A top weld line 304 including a topweld axis 306 is shown. The weld axis 306 is co-axial with the directionthat the weld is applied (in the case of laser welding). In addition, abottom weld line 308 including a bottom axis 310 is shown. In oneembodiment, it is understood that the top weld line 304 and bottom weldline 308 can be part of the same continuous weld line or can be twoseparate and distinct weld lines. The weld can be any type of weldincluding (but not limited to) bead, groove, fillet, surfacing, tack,plug, slot, friction, and resistance welds.

FIG. 3A shows a butt weld made by a laser that includes a narrow anddeep fusion zone and a narrow heat affected zone flanking the fusionzone, as will be discussed in further detail. The interface surfacebetween the first 122 and second 116 contact surfaces is perpendicularto the plane of the face. The depths of these weld zones extend alongrespective weld axes 306,310 that are parallel to the direction of loadin a face-normal direction.

Compared to TIG welding and other welding techniques, laser welding canbe advantageous by concentrating more energy at the weld site. Laserwelding also produces a more localized melt, less materialinterdiffusion, and reduced material fatigue during subsequent use.

In one example, a laser weld operation is performed on the contactinterface surface while the first piece 118 and second piece 126 areheld together using a clamp or fixture to ensure a gap between the first122 and second 116 contact surfaces is minimized.

FIG. 3A further shows the top weld line 304 having a front weld bead 320and a rear weld bead 318 prior to finishing. In addition, the bottomweld line 308 also includes a front weld bead 312 and a rear weld bead314.

FIG. 3A also shows a cross-sectional profile of a variable thicknessacross the first piece striking plate 118. The thickest portion of thefirst piece striking plate 118 has a thickness, t1. The thinnest portionof the first piece striking plate 118 has a thickness, t3. A transitionregion between the thinnest and thickest portions has a thickness, t2,that is thinner than the thickest portion, t1, but thicker than thethinnest portion, t3. The thicknesses t1,t2,t3 described abovecontribute to a particular profile of an inverted cone region, as willbe described in further detail.

FIG. 3A illustrates an upper return wall 322 and a lower return wall324. The upper and lower return walls 322,324 extend away from the firstpiece striking plate 118 toward a rear portion of the club head 100. Inother words, the upper and lower return walls 322,324 extend in ageneral direction normal to the face. It is understood that the returnwalls 322, 324 may not be perfectly perpendicular to the face plane incertain embodiments. In one embodiment, the upper and lower return walls322,324 define a portion of the cavity 344 located behind the firstpiece striking plate 118. The upper return wall 322 can be defined asthe portion of a return wall that is above a horizontal plane 342 thatis perpendicular to the face plane (parallel with the score-lines)passing through a center point 340. Subsequently, the rear lower returnwall 324 can be defined as any return wall portion below the horizontalplan 342 (toward the sole portion).

The upper and lower return walls 322, 324 can be one single continuousreturn wall that extends from the rear surface of the striking plate ortwo or more separate return wall portions. In other words, the entirereturn wall including an upper wall 322 and a lower wall 324 can extend360° about the perimeter of the cavity 344. In another embodiment, theentire return wall only extends around the perimeter of the cavity 344about 270° (relative to the center face) while excluding all or part ofthe upper wall 322 portion.

Both the top weld line 304 and bottom weld line 308 are located inwardlyaway from the upper and lower return walls 322, 324 toward the centerpoint 340 of the front striking surface of the golf club head 300. Inone embodiment, the top weld line 304 includes the weld axis 306 that isinwardly offset from the upper return wall 322 by a distance, a1(described in further detail below). Similarly, the bottom weld line 308includes the weld axis 310 that is inwardly offset from the lower returnwall 324 by a distance a1. In one embodiment, the offset distance a1 isthe same for the upper return wall 322 and lower return wall 324. Inother embodiments, the offset distance, a1, can vary around a perimeterof the striking plate 118. In one embodiment, the offset distance a1 canbe between about 1-5 mm, 1-10 mm, 1-15 mm, 1-20 mm, or at least 1 mm. Incertain embodiments, the weld axes 304,308 are equally offset from theupper and lower return walls 322,324 by the offset distance a1 at allpoints around a periphery of the striking plate 118.

FIG. 3B is an enlarged view of the bottom weld line 308 after the frontweld bead 312 (and front bead 320, not shown) has been removed bymachining or polishing to create a smooth front surface. FIG. 3Bprovides a clear view of the heat-affected zone 326 and the fusion zone328 previously mentioned. The fusion zone 328 and heat affected zone 326tend to be wider at the front surface and progressively narrower withincreasing depth of the weld. The width of the weld zone including theheat affected zone 326 and fusion zone 328 is relatively narrow comparedto a conventional weld.

At all locations around the 360° circumference of the contact interface,the respective weld axes and fusion zones extend substantially parallelto the direction of the ball impact force that is applied to the faceduring use. In one embodiment, all the weld axes are in the plane of thecontact interface to provide a sufficient butt weld. The entire weld islocated on the face of the club head and away from the return wall322,324. In other words, the entire weld is located within the cavity344 back portion of the golf club head and does not extend beyond anyreturn wall 322,324 or into any hinge region.

In one embodiment, the first piece striking plate 118 is fitted to andaligned with the second piece 126 and is moved relative to the laser302. It is understood that the laser can move relative to the assemblyor both the laser and the assembly can move. In one embodiment, thelaser is a CO₂ cw laser and has an adjustable output power in the rangeof 1350-2000 W. The welding can begin near the hosel and continue aroundthe contact interface forming the front and rear weld bead. In oneembodiment, the laser can move relative to the surface within the rangeof 40 to 80 cm/min.

After completion of the welding, the club head is subjected to a heattreatment for aging. The post-weld heat treatment is generally at480-540° C. for four hours. The club head is also machine finished asrequired, such as grinding, polishing, or sandblasting, to smooth andtopologically blend the surface of the weldment into the face plane.Finish machining is desirably followed by passivation. After completingfinish-machining, it may be desirable to apply a suitable surfacetreatment of the club head, such as plating, painting, coating, or thelike. Plating may be performed to produce a surface plating layer thatprotects against corrosion and is strong, durable, relatively inert, andaesthetically pleasing. Exemplary materials for forming a plating layerare Cr, Ni, and Cu. Exemplary techniques for forming the plating layerare electrode plating, electroless plating, physical vapor deposition(PVD), chemical vapor deposition (CVD), ion plating, andion-beam-enhanced diffusion. An intermediate sublayer can be appliedprior to the plating layer such as soft nickel, soft copper, and oxides.

FIG. 3B illustrates the weld penetrating 100% through the first piecestriking plate 118. In one embodiment, the weld penetration is at leastabout 1 mm deep or at least 90% (of the thickness of the material)penetration to maintain sufficient strength and durability. In anotherembodiment, the weld penetration is between about 1-4 mm depending onthe thickness of the material. In certain embodiments, the width of thefusion zone is about 2 mm to 3 mm wide (as measured in a plane parallelto the face plane). In one embodiment, the welding is not performed at aconstant power or speed. The output of the laser and the progressionrate of the laser around the circumference are controllably adjusted asrequired to apply more power for a longer time in regions where a deeperweld is desired.

FIG. 3B further shows a hinge region 330 or transition region locatedbetween the front striking surface 338 of the club and a lower returnwall 324. For clarity, only the lower return wall 324 is shown in FIG.3B although it is understood that a hinge region 330 can extend aroundthe all or part of the periphery of the front striking surface 338. Forexample, a hinge region 330 can extend between the upper return wall 322and front striking surface 338 as well. In one embodiment, the frontstriking surface 338 includes the first piece striking plate 118 inaddition to a portion of the second piece 126 that is within thestriking surface plane 336. In another embodiment, the fusion zone 328can be located at the very edge of the front striking surface 338 justoutside of the hinge region 330 (i.e. inward and away from the hingeregion 330). Therefore, in certain embodiments, the front strikingsurface 338 can be entirely comprised of the first piece striking plate118.

Locating the fusion zone 328 outside of the hinge region 330 allows forgreater dimensional uniformity in the hinge region 330 during casting orforming of the second piece. The hinge region 330 is formed as a portionof the second piece 126.

Placing the fusion zone 328 outside of the hinge region 330 prevents anyunintentional deformation of material within the hinge region 330ensuring consistent mechanical characteristics and performance duringimpact in the hinge region 330. The mechanical characteristics (such asstrength, bending stiffness, shear force, stress, strain, ductilityetc.) of the hinge region 330 can be negatively impacted by the presenceof a fusion zone 328 within the hinge region 330. The presence of afusion zone 328 in the hinge region can create unwanted stressconcentrations which may lead to mechanical failures.

A front striking surface plane 336 extends across the entire frontstriking surface 338 while being co-planar with the front strikingsurface 338 (excluding grooves). FIG. 3B further shows a face-hingeboundary line 332 which identifies the edge of the front strikingsurface 338 and the hinge region 330. The face-hinge boundary line 332is generally perpendicular or normal to the front striking surface plane336 around a periphery of the front striking surface 338. The face-hingeboundary line 332 is located at the point where the front strikingsurface 338 ends and a face contour or profile is no longer coplanarwith the front striking surface plane 336.

The hinge region 330 is further defined by the hinge-rear wall boundary334. The hinge-rear wall boundary 334 indicates the location where thehinge region 330 ends and the rear wall 324 begins. The hinge-rear wallboundary 334 is a plane parallel with the front striking surface plane336 offset in a rearward direction toward the back of the club head 300.In one embodiment, the hinge-rear wall boundary 334 is offset from thefront striking surface plane 336 by a distance, a2. In certainembodiments, the offset distance a2 is about 2-5 mm or about 2-20 mmtoward the rear portion of the club head 300 depending on the thicknessof the striking plate 118.

In one embodiment, the hinge-rear wall boundary 334 is primarily definedas a 1 mm offset from a rear surface plane 346. The rear surface plane346 is a plane that is generally coplanar with the rear surface of thestriking plate 118 having a relatively constant and thin thicknessimmediately outside and adjacent to the hinge region 330. In someembodiments, the rear surface plane 346 is generally perpendicular tothe face-hinge boundary line 332. The hinge-rear boundary 334 isparallel with the rear surface plane 346 and offset by a distance, a4.In a preferred embodiment, the hinge-rear boundary 334 is offset fromthe rear surface plane 346 by at least about 1 mm. In certainembodiments the offset distance, a4, is about 1 mm.

In addition, the face-hinge boundary line 332 is offset a minimumdistance, a3, from the weld line axis 310 measured across the strikingsurface plane 336. In one embodiment, the offset distance a3 is about 1mm while still remaining outside the hinge region 330. In certainembodiments, the offset distance a3 is between about 1-10 mm, andpreferably between at least about 1-5 mm or at least 1 mm. Inembodiments where the weld bead 314 does not follow the peripheralcontour of the face-hinge boundary line 332, the a3 offset distance canvary for different shaped face welds. A weld having a distance, a3, ofzero would be located directly on the face-hinge boundary line 332 andwould therefore undesirably create a weld in the hinge region 330.

In some embodiments, the a3 offset distance (related to face-hingeboundary 332) and the a1 offset distance (related to rear wall) may beequal depending on the construction. The weld axes 310,306 should alwaysbe placed outside of the hinge region and inward (toward the center) ofany return wall that may be present.

FIG. 3C illustrates a magnified hinge region according to anotherembodiment similar to FIG. 3B. However, the lower return wall 324 islocated inwardly toward the center of the club face and above theface-hinge boundary 332. A return wall plane 348 is shown to be locateda certain distance, a5, above the face-hinge boundary 332. The distancea5 can be any distance depending on the location of the rear wall 324with respect to the face-hinge boundary 332. The return wall plane 348is normal and perpendicular to the striking surface plane 336 and thehinge-rear wall boundary 334. The hinge-rear wall boundary 334intersects with a return wall profile at an intersection point 350. Thereturn wall plane 348 intersects with the hinge-rear wall boundary 334at the intersection point 350. Subsequently, the weld axes 310,306 areoffset by the offset distance a1 from the return wall plane 348. In oneembodiment, the offset distance, a1, is about 1 mm or more, as describedherein.

The location of the weld bead 314 and fusion zone 328 with respect tothe hinge region 330 is critical to achieving a high COR (coefficient ofrestitution), thin face, cavity back iron having consistent hinge regionperformance while saving mass in the face to be allocated to otherregions of the golf club head. In some embodiments, the COR is greaterthan 0.790. Preferably, the COR is at least 0.80 as measured accordingto the USGA Rules of Golf. The COR can even be as high as 0.83.

In certain embodiments, the first piece striking plate 118 can be forgedmaraging steel, maraging stainless steel, or precipitation-hardened (PH)stainless steel. In general, maraging steels have high strength,toughness, and malleability. Being low in carbon, they derive theirstrength from precipitation of inter-metallic substances other thancarbon. The principle alloying element is nickel (15% to nearly 30%).Other alloying elements producing inter-metallic precipitates in thesesteels include cobalt, molybdenum, and titanium. In one embodiment, themaraging steel contains 18% nickel. Maraging stainless steels have lessnickel than maraging steels but include significant chromium to inhibitrust. The chromium augments hardenability despite the reduced nickelcontent, which ensures the steel can transform to martensite whenappropriately heat-treated. In another embodiment, a maraging stainlesssteel C455 is utilized as the first piece striking plate 118. In otherembodiments, the first piece striking plate 118 is a precipitationhardened stainless steel such as 17-4, 15-5, or 17-7.

The first piece striking plate 118 can be forged by hot press forgingusing any of the described materials in a progressive series of dies.After forging, the first piece striking plate 118 is subjected toheat-treatment. For example, 17-4 PH stainless steel forgings are heattreated by 1040° C. for 90 minutes and then solution quenched. Inanother example, C455 stainless steel forgings are solution heat-treatedat 830° C. for 90 minutes and then quenched.

In one embodiment, the second piece 126 is made from carbon steel (e.g.,1020, 1030, or 1040 carbon steel), chrome-molybdenum steel (e.g., 4140Cr—Mo steel), Ni—Cr—Mo steel (e.g., 8620 Ni—Cr—Mo steel), austeniticstainless steel (e.g., 304, N50, or N60 stainless steel (e.g., 410stainless steel).

The second piece 126 can include various features such as weightingelements, cartridges, and/or inserts or applied bodies as used for CGplacement, vibration control or damping, or acoustic control or damping.For example, U.S. Pat. No. 6,811,496, incorporated herein by referencein its entirely, discloses the attachment of mass altering pins orcartridge weighting elements.

After forming the first piece striking plate 118 and the second piece126, the first 122 and second 116 contact surfaces can befinish-machined to ensure a good interface contact surface is providedprior to welding. In one embodiment, the first 122 and second 116contact surfaces are planar for ease of finish machining and engagement.

It is possible that an alignment aid can be used to ensure the firstpiece striking plate 118 engages with the second piece 126. In oneembodiment, an alignment aid can include an edge, lip, pin, nubbin,male-female detents, or similar aides that ensure the interface surfacesare brought into mating engagement. Moreover, the interface surfaces canhave complex complementary contours.

FIG. 4 illustrates another embodiment including a club head 400, a firstpiece striking plate 402, a top line weld 404, a top rear weld bead 418,a top weld axis 406, a striking face plane 436, a bottom line weld 408,a bottom rear weld bead 414, a bottom weld axis 410, and a face-hingeboundary line 432, as similarly described above.

FIG. 4 further shows a weld axis convergence point 440 where the topweld axis 406 and the bottom weld axis 410 intersect or converge. In theembodiment shown, the convergence point 440 occurs behind the strikingface plane 436 in a rearward direction relative to the club head 400. Itis understood that the top weld axis 406 and bottom weld axis 410 wouldform a weld axis plane as the weld is created about the periphery of thefirst piece striking plate 402. The weld axis angle 442 is createdbetween both weld axis 406,410 and the first piece striking plate 402.In one embodiment the weld axis angle 442 is between about 90° to about180°. For example, the weld axis angle 442 can be about 135°. In certainembodiments, the weld axis angle 442 is at least less than about 180°.

FIG. 5 illustrates yet another embodiment including a club head 500, afirst piece striking plate 502, a top line weld 504, a top rear weldbead 518, a top weld axis 506, a striking face plane 536, a bottom weld508, a bottom rear weld bead 514, a bottom weld axis 510, and aface-hinge boundary line 532 as similarly described above.

FIG. 5 further shows a weld axis convergence point 540 where the topweld axis 506 and the bottom weld axis 510 intersect or converge. In theembodiment shown, the convergence point 540 occurs in front of thestriking face plane 536 in a forward direction relative to the club head500. In one embodiment the weld axis angle 542 is between about 0° toabout 90° relative to the first piece striking plate 502. In certainembodiments, the weld axis angle 542 is less than 90°.

FIG. 6 illustrates another embodiment including a golf club head 600having a lap joint created between the first piece striking plate 602and the second piece 612. The golf club head 600 includes a top lineweld 604, a bottom line weld 608, a top weld axis 606, and a bottom weldaxis 610 as similarly described above. The lap joint created includes afront edge 616 located around a periphery of the striking plate 602 anda rear edge 614. In one embodiment, both the front edge 616 and the rearedge 614 are parallel with the weld axes 606,610. The weld axes 606,610are aligned with the front edge 616 so that a weld is primarily createdat the interface between the front edge 616 and the second piece 612. Itis understood that in some embodiments, the front edge 616 and rear edge614 may be non-parallel with the weld axes 606,610. In one embodiment,the maximum radial diameter of the front edge 616 across the face planeis less than the maximum radial diameter of the rear edge 614 across theface plane.

FIG. 7 illustrates another embodiment including a golf club head 700having a lap joint. The golf club head 700 further includes a firstpiece striking plate 702, a second piece 712, a top line weld 704, abottom line weld 708, a top weld axis 706, a bottom weld axis 710, afront edge 716, and a rear edge 714. In one embodiment, the maximumradial diameter of the front edge 716 is larger than the maximum radialdiameter of the rear edge 714 across the face plane. The weld axes706,710 are aligned and parallel with the front edge 716 to create aweld at the front edge 716 interface with the second piece 712.

FIG. 8 illustrates a toe view of a golf club head 800 having a hosel802, a hosel axis 804, a sole portion 806, a toe portion 808, a heelportion 810, and a top-line portion 812.

FIG. 9 is a cross-sectional view of the golf club head 800 taken alongthe cross-sectional lines 9-9 in FIG. 8, according to one embodiment.FIG. 9 illustrates a first piece striking plate 902 and rear secondpiece 904. The first piece striking plate 902 includes “inverted conetechnology” 906 (hereinafter, “ICT”), a thin face area 908, a invertedcone region edge 912, center point 914, and a rear weld bead 910. TheICT region 906 can be considered a sweet spot where an ideal impact canoccur at the center point 914. Variable thickness configurations orinverted cone configurations are discussed in, for example, U.S. Pat.Nos. 6,800,038, 6,824,475, 6,904,663, and 6,997,820, all incorporatedherein by reference.

The inverted cone region 906 is an ellipse (of which the major axis isnearly horizontal), including a central zone 906 a and a surroundingridge 906 b. In one embodiment, the thin face area 908 has a nominalthickness of about 1.8 mm. The ridge 906 b can have a thickness of about2.0 mm. In the region located between the ridge 906 b and the ICT regionedge 912, the thickness of the face tapers down to a thickness of about1.8 mm. In other embodiments, various profile thicknesses in the rangeof 1.6 mm to less than 2.5 mm are possible. In some embodiments, thethin face thickness is less than 2.0 mm. The thickness profiles and lowthickness values can be achieved during forging of the first piecestriking plate 902.

In one embodiment, a 0.5 mm to 1.0 mm machine stock plate can be addedto the first piece striking plate 902 to increase tolerance control.After forging, the first piece striking plate 902 can be slightly milledand engraved with score-lines. A key advantage of being able to forgesuch a thin face is the freeing up of discretionary mass (up to about 20g) that can be placed elsewhere in the club head (such as the rearpiece) for manipulation of the moment of inertia or center of gravitylocation.

The thickness of the first piece striking plate 902 in the thin facearea 908 is generally consistent in thickness and non-variable. Ofcourse, manufacturing tolerances may cause some variation in the thinface area 908. The thin face area 908 and the ICT region 906 can beconsidered the “unsupported” face area of the striking face because thethickness dimensions are relatively thin in those areas.

FIG. 9 further shows the weld bead 910 being offset by a distance a1(previously described in FIG. 3A) all along a perimeter of the returnwall 916. Exemplary club head geometries for representative club headsare described in Tables 1-9 below. The exemplary club heads (examples1-9) in Tables 1-9 are similar to the embodiment of FIG. 9 in that theweld bead 910 axis is offset from the return wall 916 by a minimal a1distance in the range of about 1-5 mm or at least 1 mm. In someembodiments, the a1 distance is between about 1-4 mm.

The tabulated values in Tables 1-9 are total face area, thin face area,thin face thickness, thin face area %, Inverted Cone Technology (ICT)region, and the First Piece Striking Plate Surface Area (FPSPSA).

The “total face area” is defined as the area of face contained within aface plane on a front striking portion of the club head. The “thin facearea” is defined as the portion of the first piece striking plate thatis generally unsupported, constant in thickness, and thin. For example,the thin face area 908 shown in FIG. 9 illustrates an exemplaryunsupported thin face area. The thin face area 908 excludes the invertedcone region and any region that is located outside of the weld bead 910.The “thin face thickness” is the nominal thickness of the first piecestriking plate in the thin face area 908 as shown as dimension t3, inFIG. 3A. The “thin face area %” is the percentage of the total face areathat includes a thin face area having the thickness, t3 (excluding theICT region). The thin face area percentage is the thin face area dividedby the total face area multiplied by 100. The “inverted cone region” isthe surface area contained by the variable thickness region 906 orinverted cone area. Furthermore, the “First Piece Striking Plate SurfaceArea” is the rear surface area of the first piece striking plate 902contained within the continuous weld bead 910 (including an ICT region).

Example 1

TABLE 1 Total Face Thin Face Thin Face Thin ICT Club Area Area ThicknessFace Region FPSPSA head (mm²) (mm²) (mm) Area % (mm²) (mm²) 3-iron 2,8251,633 2.1 57 541 2,175 6-iron 2,964 1,735 2.1 58 541 2,276 9-iron 3,1161,553 2.1 49 541 2,094 Wedge 3,452 1,804 2.1 52 541 2,345

Example 2

TABLE 2 Total Face Thin Face Thin Face Thin ICT Club Area Area ThicknessFace Region FPSPSA head (mm²) (mm²) (mm) Area % (mm²) (mm²) 3-iron 2,8241,876 2.4 66 527 2,403 6-iron 2,962 1,945 2.4 65 527 2,473 9-iron 3,1131,717 2.4 55 527 2,245 Wedge 3,451 2,012 2.4 58 527 2,540

Example 3

TABLE 3 Total Face Thin Face Thin Face Thin ICT Club Area Area ThicknessFace Region FPSPSA head (mm²) (mm²) (mm) Area % (mm²) (mm²) 3-iron 2,7921,242 2.5 44 388 1,631 6-iron 2,965 1,219 2.5 41 388 1,608 9-iron 3,1511,208 2.5 38 388 1,597 Wedge 3,304 1,130 2.5 34 388 1,519

Example 4

TABLE 4 Total Face Thin Face Thin Face Thin ICT Club Area Area ThicknessFace Region FPSPSA head (mm²) (mm²) (mm) Area % (mm²) (mm²) 3-iron 2,7961,313 2.2 46 247 1,560 6-iron 2,934 1,281 2.2 43 247 1,529 9-iron 3,0841,232 2.4 39 247 1,479 Wedge 3,421 1,464 2.4 42 247 1,711

Example 5

TABLE 5 Total Face Thin Face Thin Face Thin ICT Club Area Area ThicknessFace Region FPSPSA head (mm²) (mm²) (mm) Area % (mm²) (mm²) 3-iron 2,7631,906 2.4 68 314 2,220 6-iron 2,974 1,892 2.4 63 314 2,206 9-iron 3,3761,926 2.4 57 314 2,240 Wedge 3,421 1,741 2.4 50 314 2,055

Example 6

TABLE 6 Total Face Thin Face Thin Face Thin ICT Club Area Area ThicknessFace Region FPSPSA head (mm²) (mm²) (mm) Area % (mm²) (mm²) 3-iron 2,7901327 2.5 47 239 1,567 6-iron 2,958 1426 2.5 48 292 1,719 9-iron 3,1501313 2.5 41 308 1,621 Wedge 3,301 1314 2.5 39 313 1,627

Example 7

TABLE 7 Total Face Thin Face Thin Face Thin ICT Club Area Area ThicknessFace Region FPSPSA head (mm²) (mm²) (mm) Area % (mm²) (mm²) 3-iron 3,1531459 1.9 46 1,136 2,595 6-iron 3,104 1118 2.2 36 1,134 2,253 9-iron3,150 920 2.5 29 969 1,889 Wedge 3,348 922 2.5 27 1,017 1,939

The tabulated values are representative and other configurations can beprovided as described herein. It should be noted, in the above examples,that the larger the thin face area percentage and thin face area, themore mass savings can be achieved in the first piece striking plate. Inaddition, the first piece striking plate rear surface area surrounded bythe weld bead can be an indication of how much mass savings is achieved.A balance is achieved by the FPSPSA to achieve mass savings while alsolocating the weld bead in an advantageous position away from a hingearea and return wall to achieve a reliably high COR with a thin face.Also, locating the weld bead away from the hinge region will reduce thepossibility of corrosion and rust in the hinge region over time.

FIG. 10 illustrates another embodiment having similar characteristics ofthe embodiment shown in FIG. 9. A golf club head 1000 includes a firstpiece striking plate 1002, a rear piece 1004, an ICT region 1006, acenter point 1014, a return wall 1016, a thin face area 1008, and a weldbead 1010. The weld bead 1010 is strategically located in a low stresszone located within the thin face area 1008. In one embodiment, a zonehaving the lowest stress is identified in order to place the weld 1010in such a zone. Strategically placing the weld 1010 in a low stress zonereduces the likelihood that the weld will mechanically fail upon impact.FIG. 10 further shows the weld 1010 being non-conforming with theperipheral contour of the return wall 1016. In other words, the weldcontour 1010 across the face plane is independent of the return wallcontour. The same thin face area and thin face thickness dimensions ofTables 1-7 can be achieved.

FIG. 11 illustrates yet another embodiment of a golf club head 100including a first piece striking plate 1102, a second piece 1104, a thinface area 1108, a weld bead 1110, a center point 1114, and a rear wallcontour 1116. The inverted cone region is no longer present and the thinface area 1108 is a constant flat thickness (with some manufacturingtolerance variation) across the entire surface of the first piecestriking plate 1102. The weld bead 1110 is offset from the rear wallcontour 1116 by a distance, a1, as similarly described above.

The exemplary golf club heads (examples 8-9) in Tables 8 and 9 below aresimilar in construction to the embodiment shown in FIG. 11. The ICTRegion is not applicable since the first piece striking plate 1102 is aconstant thickness. Therefore, the thin face area and the first piecestriking plate area surrounded by the weld bead are the same.

Example 8

TABLE 8 Total Face Thin Face Thin Face Thin ICT Club Area Area ThicknessFace Region FPSPA head (mm²) (mm²) (mm) Area % (mm²) (mm²) 3-iron 2,9181,205 2.1 41 NA 1,205 6-iron 3,068 1,216 2.1 40 NA 1,216 9-iron 3,2201,091 2.1 34 NA 1,091 Wedge 3,440 1,067 2.1 31 NA 1,067

Example 9

TABLE 9 Total Face Thin Face Thin Face Thin ICT Club Area Area ThicknessFace Region FPSPSA head (mm²) (mm²) (mm) Area % (mm²) (mm²) 3-iron 2,782672 2.0 24 NA 672 6-iron 2,958 681 2.0 23 NA 681 9-iron 3,159 576 2.0 18NA 576 Wedge 3,354 489 2.0 14 NA 489

In the examples provided in Tables 1-9, a total face area can be in arange of about 2,700 mm² to about 3,500 mm². The FPSPSA can be in arange of about 300 mm² to about 4,000 mm², or preferably 450 mm² toabout 2,600 mm². The thin face thickness can be in a range of about 1.0mm-3.0 mm, preferably 1.5-2.5 mm, and also preferably in a range ofabout 1.6-2.0 mm. In certain embodiments, the thin face thickness isless than about 2.0 mm. The thin face area percentage can be in a rangeof about 13-70%. In embodiments having an ICT region, the ICT regionsurface area can range from about 230 mm² to about 2,000 mm².

FIG. 12A illustrates a cavity back golf club head 1200 including a clubhead portion 1202 and a badge 1204 (or third piece). The club headportion 1202 includes the entire welded club head assembly having a rearweld bead 1204, as similarly described above. The front weld bead hasbeen removed and polished according to the operations described above.However, the rear weld bead 1204 is not removed or polished and remainsexposed in the cavity and visible to a user prior to the attachment of abadge 1204. Instead of incurring addition manufacturing cost in removingthe weld bead 1204, the badge 1204 is adhesively bonded to the rearsurface of the striking face of the club head 1200. The badge obscuresthe weld bead 1204 so that no visual difference can be observed by theuser. Applying the badge 1204 allows a weld to be placed on the face ofthe iron with minimal cost. Furthermore, the badge 1204 can havedesirable effects on sound and vibration dampening upon impact with agolf ball.

FIG. 12B illustrates an assembled view of the golf club head 1200 wherethe badge 1204 has been adhesively applied with epoxy or any knownadhesive. For example, an epoxy such as 3M® DP460 can be used. It ispossible for the badge 1204 to be mechanically attached to the club headportion 1202.

FIG. 13 illustrates a series of operations 1300 that are accomplished inutilizing a badge to cover a rear face weld bead. Initially, a weld isplaced on the face of an iron-type golf club in the first operation1302. A weld bead likely occurs on the front face portion and within therear cavity portion of the golf club head. The weld bead or weld marksare removed from the front face of the golf club head while allowing therear weld bead to remain intact in a second operation 1304. Finally, therear exposed weld that is visible in the cavity is covered by anadhesively or mechanically attached 1306 badge thereby reducing the costof manufacturing and additional processing operations.

It is understood that the rear exposed weld can be partially covered bya badge or part of the rear piece (or second piece) so that at least aportion of the weld is visible within the cavity region. In someembodiments, 50% or more of the rear weld bead may be exposed or visible(while 50% or less is covered) in the cavity back region withoutdeparting from the scope of the present invention.

At least one advantage of the embodiments described is that dimensionaluniformity is achieved in the hinge region of the golf club head.Therefore, the likelihood of a “wall blowout” or failure in the hingeregion is avoided. Also, the weld is capable of being placed in a highstress location (such as on the face) due to the use of high strengthmaterials which provide additional stability to the weld line.

At least another advantage of the embodiments described is that the weldbead being located away from the hinge region and on the face of thegolf club head allows a badge to be placed in the cavity region of theclub head with minimal or no manufacturing processing.

At least another advantage of the embodiments described is that a thinface and high COR golf club can be achieved by providing furtherdimensional stability in the hinge region.

The components of the above described components disclosed in thepresent specification can be formed from any of various suitable metalsor metal alloys.

In addition to those noted above, some examples of metals and metalalloys that can be used to form the components of the connectionassemblies include, without limitation, carbon steels (e.g., 1020 or8620 carbon steel), stainless steels (e.g., 304 or 410 stainless steel),PH (precipitation-hardenable) alloys (e.g., 17-4, C450, or C455 alloys),titanium alloys (e.g., 3-2.5, 6-4, SP700, 15-3-3-3, 10-2-3, or otheralpha/near alpha, alpha-beta, and beta/near beta titanium alloys),aluminum/aluminum alloys (e.g., 3000 series alloys, 5000 series alloys,6000 series alloys, such as 6061-T6, and 7000 series alloys, such as7075), magnesium alloys, copper alloys, and nickel alloys.

In view of the many possible embodiments to which the principles of thedisclosed invention may be applied, it should be recognized that theillustrated embodiments are only preferred examples of the invention andshould not be taken as limiting the scope of the invention. It will beevident that various modifications may be made thereto without departingfrom the broader spirit and scope of the invention as set forth. Thespecification and drawings are, accordingly, to be regarded in anillustrative sense rather than a restrictive sense.

We claim:
 1. An iron-type golf club head comprising: a first pieceincluding at least a portion of an iron-type face; a second pieceincluding a hinge region; a first contact surface of the first piecebeing connected with a second contact surface of the second piece at acontact interface; a weld extending along the contact interfaceattaching the first and second pieces together at the contact interface,the continuous weld including a fusion zone occurring substantially onthe iron-type face outside the hinge region of the club head, wherein arear weld bead is exposed on a rear surface of the iron-type face. 2.The iron-type golf club head of claim 1, wherein the rear weld bead issubstantially covered by a third piece.
 3. The iron-type golf club headof claim 2, wherein the third piece is a badge.
 4. The iron-type golfclub head of claim 1, wherein a front weld bead is removed from a frontsurface of the iron-type face.
 5. The iron-type golf club head of claim1, wherein a weld centerline axis is offset from a rear wall portion bya distance of at least 1 mm.
 6. The iron-type golf club head of claim 1,wherein a total face area is between 2,700 mm²-5,000 mm².
 7. Theiron-type golf club head of claim 1, wherein a thin face area is 450mm²-2,020 mm².
 8. The iron-type golf club head of claim 1, wherein athin face thickness is about 1.5-2.5 mm.
 9. The iron-type golf club headof claim 1, wherein a thin face thickness is in a range of less than 2.0mm.
 10. The iron-type golf club head of claim 1, wherein a thin facearea percentage is about 13-70%.
 11. The iron-type golf club head ofclaim 1, wherein an inverted cone region of the first piece is about 230mm² to about 2,000 mm².
 12. The iron-type golf club head of claim 1,wherein a first piece surface area is about 300 mm² to about 4,000 mm².13. The iron-type golf club head of claim 1, wherein a coefficient ofrestitution of the golf club head is at least 0.8.
 14. The iron-typegolf club head of claim 1, wherein the first piece is forged of a steelselected from the group consisting of maraging steels, maragingstainless steels, and PH stainless steels.
 15. The iron-type golf clubhead of claim 14, wherein first piece is one of C455 and 17-4 stainlesssteel.
 16. The iron-type golf club head of claim 1, wherein the fusionzone is substantially located in a relatively low impact stress regionof the front striking surface.
 17. A golf club head comprising: a frontstriking surface; a rear face surface located behind at least a portionof the front striking surface in a cavity region; a first pieceincluding at least a portion of the front striking surface; a secondpiece including at least a portion of a hinge region; a contact surfaceof the first piece being connected with a contact surface of the secondpiece, the contact between the first piece and the second piece defininga contact interface; a weld extending along the contact interfaceattaching the first piece and the second piece together at the contactinterface, the continuous weld including a fusion zone creating a weldbead on at least the rear face surface; and a third piece attached tothe rear face surface and substantially covering the weld bead.
 18. Theclub head of claim 17, wherein the continuous weld includes a weldcenterline axis that is offset from a boundary line between the frontstriking surface and the hinge portion by a distance of at least 1 mm.